This section introduces aspects that may help facilitate a better understanding of the disclosure. Accordingly, these statements are to be read in this light and are not to be understood as admissions about what is or is not prior art.
Energy-selective X-ray imaging holds great promise at addressing major challenges in X-ray imaging and diffraction. Laue diffraction requires broad-bandwidth X-ray sources and energy assignments for each measured diffraction spot. While this assignment is currently performed by analysis of the total diffraction pattern, improvements in assignments could be enabled through independent measurements of X-ray energies. In materials analysis, the transmittance of X-rays through different materials may be highly sensitive to the X-ray wavelength, particularly at wavelengths close to spectral band-edges. Consequently, spectral X-ray imaging provides contrast intimately connected to composition for materials analysis and biomedical applications.
Particularly in imaging applications with massively parallel detection, multi-threshold photon counting strikes a reasonable cost-benefit balance between the technical requirements to record and store the raw sensor data and the inherent information content it provides. However, accurately relating the measured counts back to X-ray photon energy remains challenging. In most current systems, pixels do have adjustable thresholds, but the voltage peak height distribution is nontrivial due to several factors. These include pixel-to-pixel variance in performance, photon counting paralysis at high count rates, and the spread in the photoelectron plume over multiple pixels. Consequently, the simplest approach of setting a threshold to detect one and not the other X-ray photon energy may be subject to significant errors.
Given the many practical challenges historically associated with spectral X-ray imaging, there is an unmet need for improvements in spectral X-ray imaging.